A device as defined above is widely known. For example, a CD-player or MP3-player processes digital audio files so as to make them audible through a headphone or loudspeaker. The audio files constitute primary information of the player, since it is the player's primary function to process and play the audio files. An MP3-player comprises a digital memory for storing the audio files, while a CD-player has removable storage means, i.e. respective CDs. As another example, an organizer or personal digital assistant (PDA) enables entry, storage and retrieval of digital data, such as addresses and appointments. Such digital data constitutes primary data of the organizer or PDA since it relates to the primary function of these devices.
The primary data processed by the known devices often reflects aspects of the owner's personality, e.g. music files tell something about the owner's musical taste, and addresses and appointments tell something about the owner's occupations and circle of acquaintances.